The present disclosure relates to a liquid crystal display apparatus that includes a liquid crystal display device in which a liquid crystal layer is sealed between a pair of substrates that includes an alignment film on an opposed surface thereof.
In recent years, a liquid crystal display (LCD) has been widely used as a display monitor of a liquid crystal television, a notebook personal computer, a car navigation device or the like. The liquid crystal display has various display modes (types) according to molecular arrangement (alignment) of liquid crystal molecules included in a liquid crystal layer disposed between substrates. For example, a twisted nematic (TN) mode in which liquid crystal molecules are aligned to be twisted in a state where voltage is not applied is known as a display mode. In the TN mode, the liquid crystal molecules have a positive dielectric anisotropy, that is, a characteristic that a dielectric constant in a long axis direction of the liquid crystal molecules is larger than that in a short axis direction thereof. Thus, the liquid crystal molecules have a structure in which an alignment direction of the liquid crystal molecules sequentially rotates in a plane that is in parallel to a substrate surface to be aligned in a direction that is orthogonal to the substrate surface.
On the other hand, a vertical alignment (VA) mode in which liquid crystal molecules are aligned vertically with respect to a substrate surface in a state where voltage is not applied has attracted attention. In the VA mode, the liquid crystal molecules have a negative dielectric anisotropy, that is, a characteristic that a dielectric constant in a long axis direction of the liquid crystal molecules is smaller than that in a short axis direction thereof, and is capable of realizing a wide viewing angle compared with the TN mode.
In the liquid crystal display of such a VA mode, if voltage is applied, the liquid crystal molecules that are aligned in the vertical direction with respect to a substrate react to fall down in a direction that is parallel to the substrate due to the negative dielectric anisotropy, to thereby transmit light. However, since the falling direction of the liquid crystal molecules aligned in the vertical direction with respect to the substrate is random, the alignment of the liquid crystal molecules is disturbed by the voltage application, which causes deterioration of a response characteristic to voltage.
In order to regulate alignment of liquid crystal molecules in application of voltage, various techniques have been proposed. For example, a multi-domain vertical alignment (MVA) technique or a patterned vertical alignment (PVA) technique, or a technique that uses an alignment film (for example, refer to Japanese Unexamined Patent Application Publication No. 5-232473) have been proposed. In the MVA technique, an alignment control is performed using a slit or a rib (protrusion) to realize a wide viewing angle. In addition, recently, a structure (hereinafter, may be referred to as a fine slit structure) in which a plurality of fine slits is formed in an electrode (specifically, a pixel electrode) formed in one substrate and an electrode (specifically, a counter electrode) formed in the other substrate is provided as a so-called solid electrode having no slit has been proposed (for example, refer to Japanese Unexamined Patent Application Publication No. 2002-357830). However, in the fine slit structure, a part to which an electric field is not applied occurs in slits formed of fine lines and spaces, and an alignment state of liquid crystal molecules in application of voltage has a twisted structure, which lowers light transmittance.
In order to solve the above problem, a technique in which concave and convex portions instead of a plurality of fine slits are formed in a pixel electrode is disclosed in Japanese Unexamined Patent Application Publication No. 2011-232736. In this technique, in one pixel, the plurality of concave and convex portions includes a stem convex portion that extends on the X axis and the Y axis, and a plurality of branch convex portions that extends from side edges of the stem convex portion to the periphery of the pixel. Further, an extension direction of the side edges of the stem convex portion that is not joined to the branch convex portions is parallel to the X axis and is parallel to the Y axis.